The quantitative measurement of oxygen in the presence of combustibles, such as hydrogen or carbon monoxide, is important.
Traditional gas analysis methods, such as gas chromotography, can be used, but these methods require gas sampling and do not provide the in-situ type of analysis that allows fast control of firing conditions to prevent hazardous conditions. Thus, it is preferred to use an in-situ probe-type sensor for monitoring these potentially explosive conditions.
Conventional electrochemical potential measurements of commercially available probe-type solid electrolyte sensors are undesirable for this gas measuring application in that such devices operate at temperatures, i.e. 800.degree.-1200.degree. C., at which undesirable reactions occur between the oxygen and fuel constituents of a gas mixture.